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SOME EXPERIENCES WITH BRASS IN CIVIL 
ENGINEERING WORKS. 



A 

ALFRED D.'FtlNN. 



£ <V4.jp., I "115^ 



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JVJt ?r IS/6 



A paper to be presented at the Annual 
Meeting of the American Institute of 
Metals, September 28 to October 1, 
1915, at Atlantic City, N. J. 



10 



(Advance Copy.) 
(Not to be published before the date of the meeting. Written discussion invited.) 









PC 



SOME EXPERIENCES WITH BRASS IN CIVIL ENGINEER. 

ING WORKS. 

Alfred D. Flinn, M. Am. Soc. C. E. 1 

"Brass" is herein used to mean various copper alloys con- 
taining not over 70 per cent, of copper, including many metals 
commercially denominated bronze of one kind or another. Ex- 
periences to be described were had in connection with the unprec- 
edented new water works for New York City, commonly re- 
ferred to as the Catskill aqueduct. These experiences extend 
over the period from 1908 to this date. 

Because of the importance of the Catskill aqueduct struc- 
tures and their equipment, and because as time advances inter- 
ruptions in their use would become increasingly objectionable, 
earnest efforts were made to secure dependability and perma- 
nence, particularly in parts which could not readily be renewed. 
To this end, the most enduring materials were sought and care- 
ful investigations made to determine what was best for each pur- 
pose. Having clearly in mind the disadvantages arising from the 
corrodibility of iron and steel in hydraulic structures and the im- 
practability of preventing their corrosion, a strong, incorrodible 
metal was sought. No such metal is known of sufficiently low 
cost to be afforded even by New York City for general water- 
works uses; consequently, for pipe lines, for most of the large 
valves and all large sluice gates, and for most structural metal 
parts the Catskill aqueduct engineers were forced to be contented 
with iron and steel, protected by the best means and methods 
discoverable. 

Some few kinds of metal parts there were, however, in which 
the disadvantages of corrosion of iron or steel were so great that 

deputy Chief Engineer, Board of Water Supply of the City of New York. 



a relatively large expenditure for a strong incorrodible metal 
was justified. In most, if not all, these parts it was impracticable, 
by any known method, to protect iron or steel permanently. In- 
cluded in this category are : Sluice gate anchors and other bolts, 
the failure of which would be extremely troublesome ; large and 
small valves of ordinary and special design, inaccessible for in- 
spection and repairs or not replaceable without putting the aque- 
duct out of service for short or long periods; some special pipe 
castings situated similarly to the valves just mentioned, and per- 
manent ladders in deep gate wells or man-holes which would un- 
avoidably be wet or damp and dark. 

Having found metals which seemed well suited to these pur- 
poses at prices lower than were anticipated, these metals were 
used somewhat more extensively than at the outset intended, be- 
cause it proved economical so to do. Even as restricted, the total 
number and weight of these parts to be made of incorrodible 
metal became impressively large on so great a system of works 
as the Catskill water supply. In numbers, the bolts and other 
parts ran far into the thousands and their weight aggregated 
about 3,000,000 pounds. Of this total weight, castings ranging 
from a few ounces to 22,000 pounds each amounted to more than 
2.000,000 pounds. There were many forgings, ranging from bolts 
of ordinary sizes to sluice gate stems about 6 inches in diameter, 
31 feet long, weighing 3,200 pounds a piece. Rods, plates and 
shapes made up the balance, some rolled and drawn, others ex- 
truded. The total expenditure for the purchase of brass may 
be roughly approximated at $1,000,000. For descriptions of 
many of these objects, reference is made to a paper by the author, 
entitled, ''Brass in Engineering Construction," presented to the 
Municipal Engineers of the City of New York, in November, 
1914; also, to numerous articles in the metal trade journals dur- 
ing the past few years, as well as in the engineering periodicals. 
Accompanying illustrations show a number of them. 

Since no simple metal exists which would meet the require- 
ments, naturally the brasses and bronzes, which are among the 
oldest known alloys, were regarded as the most promising ma- 
terials. Government bronze (variously called gun metal, com- 



position G and 88-10-2), manganese bronze, naval brass, phos- 
phor bronze, Tobin bronze, vanadium bronze, Monel metal and 
some other alloys all were investigated. Bearing brasses and 
bronzes for gate and valve seats and similar parts will not enter 
into this discussion. Common brass was not seriously considered 
for the parts with which this paper is particularly concerned be- 
cause of its known corrodibility, under many circumstances. For 
some of the alloys mentioned, it was claimed that they could be 
used as steel is used and that they equalled or exceeded steel in 
strength. These claims were supported by the reports of tests 
made in government, college and professional testing laboratories 
and by records of experience. After careful consideration, man- 
ganese bronze was selected for general use for the purposes men- 
tioned. Although in no one case had this metal been used so ex- 
tensively as was proposed for the aqueduct, excepting possibly 
in the Navy, it seemed to have an excellent record in both cast- 
ings and wrought shapes. It had been in use for thirty years or 
more. Not only the United States Navy but other navies had, 
for many years, used manganese bronze propellers, some of 
which were very large castings, and manganese bronze bolts. In- 
formation was diligently sought from responsible superintend- 
ents, metallurgists and officers of large manufacturing com- 
panies, and from engineers and other users, in many different 
places, and the counsel of such men was frequently asked and 
freely given while designing and specification writing were in 
progress. 

All the brass for Catskill aqueduct was obtained under speci- 
fications and was inspected. Many bolts and other relatively 
small articles and a few of the large ones were furnished under 
special items in general contracts for the construction of large 
portions of the aqueduct, but the major portion of the brass, 
and particularly the large valves and special pipe castings, were 
purchased under a few separate contracts. These numerous and 
various brass articles were made by a number of manufacturers 
in Pennsylvania, New England, New York and New Jersey by 
methods and equipment of their own selection. Some of these 
manufacturers of brass have had experience equaling or exceed- 
ing, in number of years, the period of manufacture of modern 
steels. 



One of the inherent necessities of the construction of a great 
system of works like the Catskill water supply is that the whole 
must be completed, or substantially so, before a real working 
test, or any approximation of such a test, can be made of any im- 
portant part, or of any large piece of equipment. Their sizes 
commonly forbade any preliminary test under conditions which 
would simulate those of actual use. Nevertheless, such hydro- 
static and other tests as seemed feasible were made in addition 
to the customary tensile and other physical tests. 

Specifications, with a few exceptions, stipulated the desired 
physical qualities, without giving, at the same time, metallurgical 
composition. Methods of manufacture were rarely specified or 
even indicated. The manufacturer was believed to be more com- 
petent to determine these from his long and varied experience, 
than was the engineer. Some typical extracts from the specifica- 
tions are given below and, following them, selected representative 
results of physical tests of the materials furnished. 

Bronze Castings: 

All bronze castings shall be made of new metal, shall be 
free from objectionable imperfections and shall conform ac- 
curately to patterns. When the castings are being machined, 
if the metal shows signs of imperfect mixing, they shall be 
rejected. Unless otherwise called for in the specifications, 
or upon the drawings, bronze where indicated upon the 
drawings shall mean manganese bronze. 

Manganese Bronze: 

All manganese bronze shall be equal to Spare's, Par- 
sons' or Hyde's manganese bronze, and shall have a tensile 
strength of not less than 65,000 pounds per square inch, an 
elastic limit of not less than 45 per cent, of the ultimate ten- 
sile strength and an elongation of not less than 25 per cent, 
(in 2 inches). 



Brass Rivet Rod : 

Tensile strength of brass rivet rods shall be not less 
than 55,000 pounds per square inch. The elastic limit shall 
be not less than 30,000 pounds per square inch, and the 
elongation not less than 20 per cent. 

Stems : 

The main gate stem shall be of manganese bronze, or 
other bronze of approved composition, of such dimensions 
that when placed in tension under a load in pounds equal to 
the area of the valve opening in square inches multiplied by 
125, the minimum cross-section of the stem shall have a re- 
sultant unit stress not exceeding two-thirds the elastic limit 
of the material used. These stems shall be turned straight 
and true and shall have all threads lathe-cut. 

Rolled Bronze : 

Whenever the term ' ' Bronze ' ' is used in these specifica- 
tions in a general way, or on the drawings, without qualifica- 
tion, it shall mean manganese or vanadium bronze, or monel 
metal. Whenever the characteristics of any material are not 
particularly specified, such material shall be used as is cus- 
tomary in first-class work of the nature for which the ma- 
terial is employed. 

The minimum plrysical properties of bronze shall, except as 
otherwise specified, be as follows : 

Castings : 

Ultimate tensile strength 65,000 lb. per sq. in. 

Yield point 32,000 " " " " 

Elongation 25 per cent. 

Rolled material, thickness one inch and belong: 

Ultimate strength 72,000 lb. per sq. in. 

Yield point 36,000 " " " " 

Elongation 28 per cent. 



8 



Rolled material, thickness above one inch : 

Ultimate strength 70,000 lb. per sq. in. 

Yield point 35,000 " " " " 

Elongation 28 per cent. 

After being forged into a bar, rolled or forged bronze shall 
stand, first, hammering hot to a fine point ; second, bending cold 
through an angle of 120 degrees to a radius equal to the thickness 
of the bar. 

Typical Result of Physical Tests op Brasses Used on the 
Catskill Aqueduct. 



Yield, 

pounds per 

square inch. 


Ultimate 
strength, pounds 
per square inch. 


Elongation, 
per cent. 


Reduction, 
per cent. 


Fracture. 


Forgings : 










36,500 


73,150 


41.5 


46.8 


Irreg. 


37,500 


75,750 


35.5 


43.9 


< i 


38,250 


76,900 


35.5 


46.8 


t i 


52,500 


77,100 


31.0 




" silky 


49,300 


76,150 


33.5 




Silky cup 


50,000 


75,350 


31.0 




Irreg. silky 


43,500 


70,000 


34.0 


47.0 


Irreg. 


36,000 


67,500 


40.5 


43.5 


i t 


Castings : 










39,650 


66,000 


40.0 


. . . 


Irreg. gran. 


43,100 


68,850 


25.0 




a a 


39,950 


68,050 


29.0 


. . . 


a a 


33,000 


66,250 


25.0 


25.4 


i i 


32,750 


67,500 


30.0 


27.7 


i i 


32,250 


67,200 


36.0 


34.1 


(i 


39,500 


69,100 


39.0 




" silky 


47,500 


71,000 


40.5 




" gran. 


50,000 


70,000 


34.0 




Ang. silky 


33,250 


73,000 


30.0 


28.5 


Irreg. 


33,000 


73,500 


35.0 


34.0 


i i 


34,500 


73,250 


40.0 


36.5 


l c 


43,250 


69,950 


40.5 




Ang. silky 



Yield, Ultimate 

pounds per strength, pounds Elongation, Reduction, 
square inch. per square inch. per cent. per cent. 



Fracture. 

Irreg. deep cup 

fine gr. 
Ragged cup, 

silky 
Ang. cup silky 
Ang. fine gran. 
Irr. V 2 cup 

silky 
Forked silky 
Ang. silky 
Deep fork silky 



Some brass and bronze pipes were required in various parts 
of the Catskill waterworks, and so it was specified, for example, 
that— 

" # * * The Contractor shall furnish and deliver the 
bronze pipe for the operating piping for the section valve cyl- 
inders and other miscellaneous bronze, brass or copper pipe 



Castings-' 






44,000 


70,050 


34.0 


42,500 


69,500 


37.5 


46,000 


69,850 


33.0 


44,000 


69,600 


40.5 


41,500 


72,350 


36.5 


40,000 


68,000 


38.0 


42,000 


67,000 


37.0 


43,750 


69,050 


37.0 



' ' The pipe shall be seamless drawn, semi-annealed, iron-pipe- 
size tubing of the sizes shown on the contract drawings or or- 
dered. It shall be made of the bronze specified in the general 
sections, or of an approved commercial bronze. All pipe fur- 
nished under this item shall be free from season cracks, surface 
cracks, or other defects. 

"When the pipe is finished, ready for shipment, the En- 
gineer will subject about one per cent, of the lot, taken at ran- 
dom, to the following tests : 

"1st. Each test pipe shall stand threading perfectly, with 
a die with the usual thread for the size of the pipe. 

"2nd. After annealing, the end of each test pipe shail 
stand being flattened by hammering until the sides are brought 



10 

parallel, with a curve on the inside at the ends not greater than 
twice the thickness of the metal, without showing cracks or flaws. 

"3rd. After annealing, each test-piece shall have a piece 
3 inches long cut from it, which, when split, shall stand opening 
out flat without showing cracks or flaws." 

In spite of the care exercised, the brass furnished has proved 
distinctly unsatisfactory in most of the uses to which it has been 
put in the Catskill aqueduct. No suspicions of definite troubles 
were developed until the fall of 1913. About that time numerous 
bolts and rods were found cracked. The number and character 
of the failures detected strongly suggested that they were not 
merely accidental or occasional. Since that time, additional fail- 
ures have been coming to light almost continually. Failures were 
the more disturbing because the specifications had been drawn 
carefully, in the light of information then in hand, and prac- 
tically all the metal accepted had been carefully inspected and 
tested. Some chemical analyses had been made also. Much of 
the metal accepted had shown physical qualities far in excess of 
the specified requirements. Furthermore, the objects which are 
being found defective were furnished by manufacturers of long 
experience and established reputation. It is quite improbable 
that these manufacturers had not, at least in the main, honestly 
endeavored to fulfill the requirements of their contracts, although 
they may have been insufficiently informed as to means and 
methods in some instances, and somewhat influenced by com- 
mercial considerations. 

That apparently sound brass pipes and brass wire of some 
kinds would occasionally crack, without evident reason, was 
known to the engineers of the Board of Water Supply, as were 
various explanations of this phenomenon; but leading manufac- 
turers of brass pipe had learned how to modify the process of 
manufacturing so as to overcome these troubles in large measure. 
Nevertheless, some failures have been experienced with the pipes 
furnished even by reputable manufacturers. There would seem 
to be but small excuse for supplying other than dependable brass 
(or bronze) pipe nowadays, as correct methods of manufacture 
are claimed to be well known in the trade. 



11 

Defects in large plates, in bolts, rods, side-bars and rungs of 
ladders, and in similar wrought objects constituted the most im- 
portant and numerous failures discovered up to the spring of 
1915. Many of these articles had not yet been installed, but 
had been in storage, in some instances, for many months. Many 
were still in their packing cases. Defective bolts and rods usually 
had circumferential cracks, partially or all the way around. Flats 
had cracks starting in from an edge with a characteristic curva- 
ture. Some cracks were very fine and only superficial; others 
gaped open and penetrated the metal deeply. In some cases, the 
whole or nearly the whole cross-section was affected in bolts from 
% to 2% in. in diameter; some were found severed, and others 
broke upon being subjected to a light blow or pull. Cracking has 
been progressive in some instances, and in numerous cases speci- 
mens which, on first examination seemed free from this cracking, 
developed it later; two or three years have passed in some cases 
before the defects developed so as to be detected. 

Finally, these defects were found to be so general, were so 
distributed through the output of various manufacturers, and 
were so common in the different kinds of brass that all wrought 
brass fell under suspicion. Consequently, bolts in all import- 
ant places, even when seemingly sound, ladders, pipes and other 
wrought brass objects have been or are being replaced. Following 
the first discovery of the cracking, replacements were directed to 
be made with brass produced by methods avoiding cold working, 
and special attention was given to the production of this ma- 
terial. It was hoped that, by these methods, further trouble of 
this kind would be avoided, but, unfortunately, this has not 
proved to be the case. Ultimately there has seemed to be no 
remedy other than to use steel or iron, with their known disad- 
vantages, burying them in concrete or mortar, wherever this was 
feasible even at some inconvenience, galvanizing them in other 
places and using other protective coatings in still other places. 
Indeed, but for the seriousness of the matter, "bronze" (brass) 
would be but a laughing-stock among the engineers of the Catskill 
aqueduct, and many others who have known of their experiences, 
and among those who, themselves, have had somewhat similar 
experiences within recent years, for investigation has disclosed 



12 

the fact that similar defects have been observed by others in a 
variety of metals, but, chiefly, in bolts of well known brands of 
"bronze" furnished by well known manufacturers. That such 
troubles should suddenly have developed so extensively, or, at 
least, that they should have become widely known only recently, 
or that knowledge of such failures, if they have been frequent in 
years gone by, should have been withheld by the manufacturers, 
seems incredible. The questions naturally arise : 

"Were any changes made in the methods of manufacture 
or in the ingredients of these alloys about the time that the 
production of brass for the Catskill aqueduct began ? 

What were these changes and why were they made? 

What changes, if any, have been made by the manufac- 
turers in their processes, materials and methods since the 
troubles with various brasses and bronzes on the Catskill 
aqueduct were discovered and made known? 

If no changes have been made, is it to be inferred that 
the manufacturers still believe that the methods and ma- 
terials used in producing brass for the Catskill aqueduct 
were satisfactory ? If so, how are the failures accounted for ? 

Large forgings, which include chiefly the stems for large 
sluice gates and valves, have shown no sign whatever of failure, 
although they have been repeatedly and carefully examined. Un- 
til the spring of 1915, castings were believed to be immune from 
troubles, excepting those incident to foundry work and of the 
kinds which might occur in any metal. Since then, however, 
a number of castings from at least three different foundries pro- 
ducing manganese bronze have been found cracked. All these 
castings, before acceptance, had been subjected to hydrostatic 
test pressures of 200 or 300 pounds per square inch, for a half 
hour or more, and, of course, appeared to be satisfactory at the 
time of preliminary acceptance. Some months later, after hav- 
ing been placed in the structures, some of these castings leaked 
under pressures of only a few pounds. In some castings the 



cracks have grown longer as time has elapsed, and in some, with 
the passage of time, additional cracks have been discovered. 
These cracks are fine and often difficult to detect on the surface 
until the casting is put under hydrostatic pressure. In most 
cases, indeed in nearly all, these cracks appeared to be close to, 
or in a repair made by the method of ' ' burning-in, ' ' or welding. 
Extended, recent inquiries show that this practice is of long 
standing and of general use in reputable brass foundries. 
Methods vary widely in detail. Our investigation has not yet 
proceeded far enough to justify any further statement, but it is 
evident that the application and details of such methods of re- 
pair, and some other details of brass foundry practice, need to 
be carefully studied by foundry metallurgists. 

Troubles with wrought brass or bronze, experienced on the 
Catskill aqueduct may be classified as follows : First, breaks 
from stress, (a) initial stress, due to methods of manufacture or 
fabrication, (b) applied stress, due to use; second, damage by 
wrong heat treatment, as in forging, bending, flanging, upset- 
ting and annealing. Damage of the secod class results entirely 
from lack of skill, knowledge or care on the part of the manu- 
facturer or fabricator. 

Designers have been misled to some degree by the representa- 
tions of the manufacturers that certain bronzes (brasses) pos- 
sessed great strength and other excellent qualities, and in some 
cases would perform practically the same duty as steel, or a little 
more. Seemingly both maker and user have misinterpreted the 
results of the usual standard laboratory tests, from lack of 
knowledge of characteristics of the copper alloys not revealed by 
such tests. Experience on the Catskill aqueduct indicates that 
the bronzes (brasses) as supplied under contract, with careful 
inspection following the established methods, would not perform 
the expected duty. Indeed, as these investigations have pro- 
ceeded it has become evident that the engineer's present necessity 
is not merely an explanation of certain failures of brass, but a 
fundamental knowledge of the physical characters and capacities 
of this group of alloys, — knowledge which will be a safe 8nd de- 
pendable guide in their manufacture, inspection and use. 



14 

As our investigations and experience have progressed, not 
merely unfortunate foundry and shop ignorance of important 
details of manufacture of copper alloys and, possibly, suppres- 
sion of significant information, have come to light, but, also, seem- 
ingly, a deplorable lack of definite and sufficiently complete 
knowledge of some of the fundamental characteristics of these 
alloys. Clearly, the art of brass-making had not surely pro- 
gressed so far as was confidently claimed. Before designing and 
constructing, civil and mechanical engineers can venture to use 
brass extensively for important works where it would be sub- 
jected to other than very low stresses, some questions will have 
to be conclusively answered by manufacturers and metallurgical 
specialists. The author ventures to repeat the questions, which 
he has stated more than once before, and to add to them : 

Can a brass or bronze of high tensile strength be reliably 
produced which can be used safely for important, permanent 
structures in such parts as bolts and other rolled, drawn, 
extruded or forged shapes? 

What should be the specifications for such brasses or 
bronzes ? 

What inspection methods and tests should be used ? 

By what tests can the tendency to subsequent failure be 
detected at any time after manufacture? 

What working stresses may be used safely for these 
various alloys? 

Will these brasses, or bronzes, deteriorate by reason of 
constantly applied or frequently repeated stress — i. e., will 
they fail from fatigue ? 

Can large, hollow, manganese bronze castings be made 
of such forms as water and steam valves ? 

If manganese bronze is not suitable for such castings, 
what composition can be used? 

Can any repairs of brass castings, to be subjected to 
hydrostatic pressure, be safely made by any processes of 



15 

1 ' burning-in, ' ' or welding, now commonly used ? If so, what 
relation has the shape and size of the casting to the methods 
and means to be employed? 

What tests can be applied to prove that such a repair 
has been successfully made and that later a crack will not 
develop because of it ? 

In closing, the author would disclaim any knowledge of 
metals other than as a civil engineer user, and that which he ha§ 
recently acquired by extended inquiry. The metallurgical ques- 
tions involved in the experiences narrated above are being inves- 
tigated by Dr. George K. Burgess and Dr. P. D. Merica with 
their staff in the Bureau of Standards, Department of Commerce, 
Washington. Mr. Ernst Jonson, engineer inspector of the Board 
of Water Supply has also devoted much time and study to these 
problems. These men have presented papers to several of the 
technical societies and journals, stating some of the results of 
their investigations. Doubtless, also, metallurgists connected with 
the manufacturers have been giving attention to these problems 
and could contribute to the general information, if they would. 
Possibly the time is not yet ripe for such statements, pending the 
further progress of experiments on an extensive scale. The de- 
mand for a strong, dependable, incorrodible metal, which can be 
cast and wrought, is so great that there would be a large use for 
it in important engineering works, even at a price several times 
that of iron or steel. The statements above have been made for 
the purpose of helping toward the production of such a metal 
and toward developing suitable methods of manufacturing, using, 
specifying and testing it. 



16 




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Catskill Aqueduct, City Tunnel. 

Section-Valve Shaft Showing 66-in. Bronze Section Valve and Adjacent Bronze 
Castings, and Method of Reducing the Diameter of the 
Tunnel to that of the Valve. 



24 




Cat skill Aqueduct, City Tunnel. 
Bronze Reducer Pipes suspended over the Shaft ready to be lowered into position. 



Valve chamber — 
at top of shaft -= 




RISER VALVE 

10 10 20 30 40 50' 60 70 Cm. 



Catskill Aqueduct City Tunnel. 

Typical Shaft and Chamber Showing Connection from the Tunnel to the Water 
Mains under the Streets; also a Shaft Cap and Riser Valve. 



26 



(Streetor park surfa ce Bronze ape for 



r-dimih cf shaft con astt n t 




B.W.5.898 SEC 



Catskill Aqueduct City Tunnel. 

Plan and Longitudinal Section of a Section- Valve Shaft Showing Special Arrange- 
ment of Risers and Positions of Riser Valves with Steel Pedestals. 



11 




Catskill Aqueduct, Pressure Tunnels. 



Bronze Door in Drift Connecting a Drainage Shaft with the Tunnel. When Door 

is Closed, Water from the Tunnel is Shut Off from the Shaft. 

Six of These Have Been Used. 



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